The present application includes a computer program listing appendix on compact disc. Two duplicate compact discs are provided herewith. Each compact disc contains an ASCII text file of the computer program listing as follows:
The computer program listing appendix is hereby expressly incorporated by reference in the present application.
The present invention relates broadly to microscopes, more particularly to a method and apparatus for supplying power to a source of illumination in a microscope, and, even more particularly, to a method and apparatus for gradually supplying power to a source of illumination in a microscope using pulse width modulation to reduce stress on the illumination filament and preserve life of the illumination source.
Microscopes use various types of illumination sources to provide the necessary light to illuminate the specimen being examined. Many different factors affect the life of these illumination sources, including the amount of time that the source is energized. Another factor that directly affects illumination source life is the induced stress on a cold filament caused by cold starting at full rated potential. Such full rated potential cold starting can cause deterioration of the filament structure and can lead to premature failure. While various methods for soft-starting illumination sources have been developed, existing methods control the rate of rise of the potential across an illumination source with passive/analog components. Although electronic circuits with passive components can reduce the deterioration process, a method of digitally controlling the turn-on time for a source of illumination would offer many advantages over other methods. Heretofore, such a digital method has not been known in the art.
Thus, it is seen that there is a longfelt need for a method and apparatus for gradually supplying power digitally to an illumination source in a microscope.
The invention broadly comprises a method and apparatus for gradually supplying power to a source of illumination in a microscope. The apparatus includes a power transistor operatively arranged to provide a varying applied voltage to the source of illumination, and means for biasing the power transistor with a pulse width modulated signal to incrementally increase the applied voltage to the source of illumination in a plurality of discrete steps. The method comprises gradually supplying power to a source of illumination in a microscope by biasing a power transistor with a pulse width modulated signal to incrementally increase the applied voltage to the source of illumination in a plurality of discrete steps.
A general object of the invention is to provide a method and apparatus for gradually supplying power to a source of illumination in a microscope by biasing a power transistor with a pulse width modulated signal to incrementally increase the applied voltage to the source of illumination in a plurality of discrete steps.
Another object of the invention is to provide a method and apparatus for supplying power to a source of illumination in a microscope which preserves source filament life.
Still another object of the invention is to provide a method and apparatus for supplying power to a source of illumination in a microscope which reduces stress induced on a source filament and prevents premature failure of the light source.
These and other objects, features and advantages of the present invention will become readily apparent to those having ordinary skill in the art from a reading and study of the following detailed description of the invention, in view of the drawing and appended claims.